The skin is a natural barrier to the penetration of foreign substances. The stratum corneum is the superficial cornified layer of the skin which provides a barrier to water evaporation and reduces the permeation of undesirable molecules from the external environment. The stratum corneum consists of dead cells called corneocytes, that are embedded in a lipid-rich matrix of fatty-acids, ceramides, and cholesterols. This structure of corneocytes embedded in lipids is thought to provide many of the barrier properties of the skin. Substances deposited on the skin must traverse this structure through a tortuous path to gain access to the underlying viable layers of the skin. Skin inflammation occurs when substances that are irritating to the skin are able to penetrate this barrier and initiate an elaborate cascade of immunological events once they contact the skin cells in the viable epidermis and dermis layers. As the skin barrier is compromised, the skin is subject to inflammatory events from percutaneous absorption of irritants through the stratum corneum.
Skin barrier function can be compromised by a variety of insults that cause inflammation. Insults to the skin can include, but are not limited to, environmental irritants, mechanical abrasion, continuous tissue load pressure, exposure to body fluids and waste, and exposure to chemicals. For example, physical and chemical treatments, abrasion, tape stripping, ultrasonics, electrical fields, enzymes, solvents, surfactants, and elevated ambient humidity are known to diminish skin barrier function. Bodily fluids and wastes may contain skin irritants in the form of enzymes such as proteases, ureases and lipases. Enzymes found in feces cleave the epidermis, dermis, and stratum corneum proteins and lipids and cause the breakdown of the natural barrier of the skin. Bacterial ureases on the skin convert the urea from urine to ammonia on the skin, causing an alkaline pH and leading to irritation of the skin. Prolonged exposure of the skin to these enzymes is thought to be a major cause of skin damage that leads to subsequent skin breakdown and contact dermatitis. In addition, the care of skin in individuals with ostomies is difficult due to the frequent contact of digestive enzymes with the skin surrounding the ostomy site. These enzymes can degrade the skin surface and cause severe skin breakdown and the development of partial thickness wounds.
Of particular concern is the formation of pressure ulcers in incapacitated individuals, such as bed-ridden patients, mentally challenged persons who are unable to perform personal hygiene, individuals who are incontinent, or hospital patients recovering from surgery to accidental trauma. These individuals may be subject to the formation of pressure ulcers due to prolonged tissue loads on parts of the body resulting from long periods of remaining in a stationary position, exposure of the skin to feces and urine, or a combination of these circumstances. Pressure ulcers frequently occur in the sacral coccyx area of the spine, however, these ulcers can also occur on hips, feet, and the skin covering elbows and shoulder blades.
A number of approaches are known for protecting the skin against the action of skin irritants and subsequent skin breakdown. Examples include protective apparel, skin protectant formulations, and anti-inflammatory compositions. Protective apparel garments may prevent irritants from contacting the skin, or may be used to prevent dissemination of irritants from bodily fluids to the surrounding environment, for example, diapers or adult incontinence garments. However, the use of barrier materials in these garments prevents movement of moisture and air and therefore, proliferates an environment in which skin may be kept in contact with the irritants and increase the damage.
Many of the skin protectant formulations commercially available may not provide adequate protection against skin irritants. Many of these formulations consist of petrolatum which can rub off onto garments and may affect the absorbency of disposable absorbent articles used as protective apparel.
Disposable absorbent products currently find widespread use in many applications. For example, in the infant and child care areas, diapers and training pants have generally replaced reusable cloth absorbent articles. Other typical disposable absorbent products include feminine care products such as sanitary napkins or tampons, adult incontinence products, and health care products such as surgical drapes or wound dressings. A typical disposable absorbent product generally comprises a composite structure including a top sheet, a back sheet, and an absorbent structure between the top sheet and back sheet. These products usually include some type of fastening system for fitting the product onto the wearer.
Disposable absorbent products are typically subjected to one or more liquid insults, such as exposure to urine, menses, blood, and feces during use. As such, the outer cover back sheet materials of the disposable absorbent products are typically made of liquid-insoluble and liquid impermeable materials, such as polypropylene films, that exhibit a sufficient strength and handling capability so that the disposable absorbent product retains its integrity during use by a wearer and does not allow leakage of the liquid insulating the product. These products are used for incontinent adults, especially bed-ridden or incapacitated individuals. The combination of skin contact with urine and feces, and the lack of air flow in garments consisting of these disposable absorbent articles can contribute to the irritation of skin leading to the development of partial and full thickness wounds and pressure ulcers.
An additional area of concern to care recipients and care givers alike is the effective management of odors arising from urinary incontinence. Soiled clothes, bedding, and disposable incontinence garments and pads can generate malodorous compounds such as isovaleric acid and other short chain organic acids, trimethylamine, ammonia, and a wide range of sulfides including dimethyl disulfide and dimethyl sulfide. The natural flora on the skin surface contain bacterial ureases which are responsible for the biotransformation of urea from urine into ammonia which is the most noticeable malodor in acute care, long term care and a home based caregiver settings. The organisms most frequently associated with the development of the above cited malodorous compounds are Klebsiella pneumoniae, Eschericia coli, and Proteus mirabilis. Other species present as normal flora can include a vast variety of gram negative and positive bacteria and fungi. The dominant offensive malodors arising from urine biotransformation and urine decomposition are sulfurous compounds and ammonia.
Past approaches to the problem have resulted in partial control of some of the odors present, notably ammonia. These approaches have included chelating chemistries such as disodium EDTA, adsorption materials such as activated carbon or charcoal and zeolites, and partially neutralized acrylic acid polymers. Combinations of these additives are well known in the art.
The development of malodorous compounds has been shown to be delayed for several hours during the effective wear period of the garment (5-8 hours) by the application of a wide range of anti-microbial compounds including mild cosmetic preservatives such as methylparaben, ethylparaben, or butylparaben.
Of particular use are sparingly water soluble and water insoluble compounds which are thought to impact the normal flora of the skin in a minimal way since they are not carried by the moisture of urine on the pad to the skin surface. Maintaining the normal flora is an important consideration in the management of healthy skin. Concerns about the development of resistant strains of bacteria has brought about the need for effective management of incontinence odors without aggressing the normal flora of the care recipient.
What is needed in the art are disposable absorbent articles comprising skin health treatment additives that can be pre-applied to the absorbent article to provide the skin with a barrier to prevent contact with irritants. What is also needed in the art are disposable absorbent articles comprising odor control additives. These and other needs are provided by the present invention.